/***************************************************************************
*                               Compression.cs
*                            -------------------
*   begin                : May 1, 2002
*   copyright            : (C) The RunUO Software Team
*   email                : info@runuo.com
*
*   $Id: Compression.cs 644 2010-12-23 09:18:45Z asayre $
*
***************************************************************************/

/***************************************************************************
*
*   This program is free software; you can redistribute it and/or modify
*   it under the terms of the GNU General Public License as published by
*   the Free Software Foundation; either version 2 of the License, or
*   (at your option) any later version.
*
***************************************************************************/

using System;
using System.Runtime.InteropServices;

namespace Server.Network
{
    /// <summary>
    /// Handles outgoing packet compression for the network.
    /// </summary>
    public static class Compression
    {
        private static readonly int[] _huffmanTable = new int[514]
        {
            0x2, 0x000, 0x5, 0x01F, 0x6, 0x022, 0x7, 0x034, 0x7, 0x075, 0x6, 0x028, 0x6, 0x03B, 0x7, 0x032,
            0x8, 0x0E0, 0x8, 0x062, 0x7, 0x056, 0x8, 0x079, 0x9, 0x19D, 0x8, 0x097, 0x6, 0x02A, 0x7, 0x057,
            0x8, 0x071, 0x8, 0x05B, 0x9, 0x1CC, 0x8, 0x0A7, 0x7, 0x025, 0x7, 0x04F, 0x8, 0x066, 0x8, 0x07D,
            0x9, 0x191, 0x9, 0x1CE, 0x7, 0x03F, 0x9, 0x090, 0x8, 0x059, 0x8, 0x07B, 0x8, 0x091, 0x8, 0x0C6,
            0x6, 0x02D, 0x9, 0x186, 0x8, 0x06F, 0x9, 0x093, 0xA, 0x1CC, 0x8, 0x05A, 0xA, 0x1AE, 0xA, 0x1C0,
            0x9, 0x148, 0x9, 0x14A, 0x9, 0x082, 0xA, 0x19F, 0x9, 0x171, 0x9, 0x120, 0x9, 0x0E7, 0xA, 0x1F3,
            0x9, 0x14B, 0x9, 0x100, 0x9, 0x190, 0x6, 0x013, 0x9, 0x161, 0x9, 0x125, 0x9, 0x133, 0x9, 0x195,
            0x9, 0x173, 0x9, 0x1CA, 0x9, 0x086, 0x9, 0x1E9, 0x9, 0x0DB, 0x9, 0x1EC, 0x9, 0x08B, 0x9, 0x085,
            0x5, 0x00A, 0x8, 0x096, 0x8, 0x09C, 0x9, 0x1C3, 0x9, 0x19C, 0x9, 0x08F, 0x9, 0x18F, 0x9, 0x091,
            0x9, 0x087, 0x9, 0x0C6, 0x9, 0x177, 0x9, 0x089, 0x9, 0x0D6, 0x9, 0x08C, 0x9, 0x1EE, 0x9, 0x1EB,
            0x9, 0x084, 0x9, 0x164, 0x9, 0x175, 0x9, 0x1CD, 0x8, 0x05E, 0x9, 0x088, 0x9, 0x12B, 0x9, 0x172,
            0x9, 0x10A, 0x9, 0x08D, 0x9, 0x13A, 0x9, 0x11C, 0xA, 0x1E1, 0xA, 0x1E0, 0x9, 0x187, 0xA, 0x1DC,
            0xA, 0x1DF, 0x7, 0x074, 0x9, 0x19F, 0x8, 0x08D, 0x8, 0x0E4, 0x7, 0x079, 0x9, 0x0EA, 0x9, 0x0E1,
            0x8, 0x040, 0x7, 0x041, 0x9, 0x10B, 0x9, 0x0B0, 0x8, 0x06A, 0x8, 0x0C1, 0x7, 0x071, 0x7, 0x078,
            0x8, 0x0B1, 0x9, 0x14C, 0x7, 0x043, 0x8, 0x076, 0x7, 0x066, 0x7, 0x04D, 0x9, 0x08A, 0x6, 0x02F,
            0x8, 0x0C9, 0x9, 0x0CE, 0x9, 0x149, 0x9, 0x160, 0xA, 0x1BA, 0xA, 0x19E, 0xA, 0x39F, 0x9, 0x0E5,
            0x9, 0x194, 0x9, 0x184, 0x9, 0x126, 0x7, 0x030, 0x8, 0x06C, 0x9, 0x121, 0x9, 0x1E8, 0xA, 0x1C1,
            0xA, 0x11D, 0xA, 0x163, 0xA, 0x385, 0xA, 0x3DB, 0xA, 0x17D, 0xA, 0x106, 0xA, 0x397, 0xA, 0x24E,
            0x7, 0x02E, 0x8, 0x098, 0xA, 0x33C, 0xA, 0x32E, 0xA, 0x1E9, 0x9, 0x0BF, 0xA, 0x3DF, 0xA, 0x1DD,
            0xA, 0x32D, 0xA, 0x2ED, 0xA, 0x30B, 0xA, 0x107, 0xA, 0x2E8, 0xA, 0x3DE, 0xA, 0x125, 0xA, 0x1E8,
            0x9, 0x0E9, 0xA, 0x1CD, 0xA, 0x1B5, 0x9, 0x165, 0xA, 0x232, 0xA, 0x2E1, 0xB, 0x3AE, 0xB, 0x3C6,
            0xB, 0x3E2, 0xA, 0x205, 0xA, 0x29A, 0xA, 0x248, 0xA, 0x2CD, 0xA, 0x23B, 0xB, 0x3C5, 0xA, 0x251,
            0xA, 0x2E9, 0xA, 0x252, 0x9, 0x1EA, 0xB, 0x3A0, 0xB, 0x391, 0xA, 0x23C, 0xB, 0x392, 0xB, 0x3D5,
            0xA, 0x233, 0xA, 0x2CC, 0xB, 0x390, 0xA, 0x1BB, 0xB, 0x3A1, 0xB, 0x3C4, 0xA, 0x211, 0xA, 0x203,
            0x9, 0x12A, 0xA, 0x231, 0xB, 0x3E0, 0xA, 0x29B, 0xB, 0x3D7, 0xA, 0x202, 0xB, 0x3AD, 0xA, 0x213,
            0xA, 0x253, 0xA, 0x32C, 0xA, 0x23D, 0xA, 0x23F, 0xA, 0x32F, 0xA, 0x11C, 0xA, 0x384, 0xA, 0x31C,
            0xA, 0x17C, 0xA, 0x30A, 0xA, 0x2E0, 0xA, 0x276, 0xA, 0x250, 0xB, 0x3E3, 0xA, 0x396, 0xA, 0x18F,
            0xA, 0x204, 0xA, 0x206, 0xA, 0x230, 0xA, 0x265, 0xA, 0x212, 0xA, 0x23E, 0xB, 0x3AC, 0xB, 0x393,
            0xB, 0x3E1, 0xA, 0x1DE, 0xB, 0x3D6, 0xA, 0x31D, 0xB, 0x3E5, 0xB, 0x3E4, 0xA, 0x207, 0xB, 0x3C7,
            0xA, 0x277, 0xB, 0x3D4, 0x8, 0x0C0, 0xA, 0x162, 0xA, 0x3DA, 0xA, 0x124, 0xA, 0x1B4, 0xA, 0x264,
            0xA, 0x33D, 0xA, 0x1D1, 0xA, 0x1AF, 0xA, 0x39E, 0xA, 0x24F, 0xB, 0x373, 0xA, 0x249, 0xB, 0x372,
            0x9, 0x167, 0xA, 0x210, 0xA, 0x23A, 0xA, 0x1B8, 0xB, 0x3AF, 0xA, 0x18E, 0xA, 0x2EC, 0x7, 0x062,
            0x4, 0x00D
        };

        private const int CountIndex = 0;
        private const int ValueIndex = 1;

        // UO packets may not exceed 64kb in length
        private const int BufferSize = 0x10000;

        // Optimal compression ratio is 2 / 8;  worst compression ratio is 11 / 8
        private const int MinimalCodeLength = 2;
        private const int MaximalCodeLength = 11;

        // Fixed overhead, in bits, per compression call
        private const int TerminalCodeLength = 4;

        // If our input exceeds this length, we cannot possibly compress it within the buffer
        private const int DefiniteOverflow = ((BufferSize * 8) - TerminalCodeLength) / MinimalCodeLength;

        // If our input exceeds this length, we may potentially overflow the buffer
        private const int PossibleOverflow = ((BufferSize * 8) - TerminalCodeLength) / MaximalCodeLength;

        private static readonly object _syncRoot = new object();

        private static readonly byte[] _outputBuffer = new byte[BufferSize];

        [Obsolete("Use Compress( byte[], int, int, ref int ) instead.", false)]
        public static void Compress(byte[] input, int length, out byte[] output, out int outputLength)
        {
            outputLength = 0;
            output = Compress(input, 0, length, ref outputLength);
        }

        public unsafe static byte[] Compress(byte[] input, int offset, int count, ref int length)
        {
            if (input == null)
            {
                throw new ArgumentNullException("input");
            }
            else if (offset < 0 || offset >= input.Length)
            {
                throw new ArgumentOutOfRangeException("offset");
            }
            else if (count < 0 || count > input.Length)
            {
                throw new ArgumentOutOfRangeException("count");
            }
            else if ((input.Length - offset) < count)
            {
                throw new ArgumentException();
            }

            length = 0;

            if (count > DefiniteOverflow)
            {
                return null;
            }

            lock (_syncRoot)
            {
                int bitCount = 0;
                int bitValue = 0;

                fixed (int* pTable = _huffmanTable)
                {
                    int* pEntry;

                    fixed (byte* pInputBuffer = input)
                    {
                        byte* pInput = pInputBuffer + offset, pInputEnd = pInput + count;

                        fixed (byte* pOutputBuffer = _outputBuffer)
                        {
                            byte* pOutput = pOutputBuffer, pOutputEnd = pOutput + BufferSize;

                            while (pInput < pInputEnd)
                            {
                                pEntry = &pTable[*pInput++ << 1];

                                bitCount += pEntry[CountIndex];

                                bitValue <<= pEntry[CountIndex];
                                bitValue |= pEntry[ValueIndex];

                                while (bitCount >= 8)
                                {
                                    bitCount -= 8;

                                    if (pOutput < pOutputEnd)
                                    {
                                        *pOutput++ = (byte)(bitValue >> bitCount);
                                    }
                                    else
                                    {
                                        return null;
                                    }
                                }
                            }

                            // terminal code
                            pEntry = &pTable[0x200];

                            bitCount += pEntry[CountIndex];

                            bitValue <<= pEntry[CountIndex];
                            bitValue |= pEntry[ValueIndex];

                            // align on byte boundary
                            if ((bitCount & 7) != 0)
                            {
                                bitValue <<= (8 - (bitCount & 7));
                                bitCount += (8 - (bitCount & 7));
                            }

                            while (bitCount >= 8)
                            {
                                bitCount -= 8;

                                if (pOutput < pOutputEnd)
                                {
                                    *pOutput++ = (byte)(bitValue >> bitCount);
                                }
                                else
                                {
                                    return null;
                                }
                            }

                            length = (int)(pOutput - pOutputBuffer);
                            return _outputBuffer;
                        }
                    }
                }
            }
        }

        public static readonly ICompressor Compressor;

        static Compression()
        {
            if (Core.Unix)
            {
                if (Core.Is64Bit)
                {
                    Compressor = new CompressorUnix64();
                }
                else
                {
                    Compressor = new CompressorUnix32();
                }
            }
            else if (Core.Is64Bit)
            {
                Compressor = new Compressor64();
            }
            else
            {
                Compressor = new Compressor32();
            }
        }

        public static ZLibError Pack(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return Compressor.Compress(dest, ref destLength, source, sourceLength);
        }

        public static ZLibError Pack(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            return Compressor.Compress(dest, ref destLength, source, sourceLength, quality);
        }

        public static ZLibError Unpack(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return Compressor.Decompress(dest, ref destLength, source, sourceLength);
        }
    }

    public interface ICompressor
    {
        string Version { get; }

        ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength);

        ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality);

        ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength);
    }

    public sealed class Compressor32 : ICompressor
    {
        [DllImport("zlib32")]
        private static extern string zlibVersion();

        [DllImport("zlib32")]
        private static extern ZLibError compress(byte[] dest, ref int destLength, byte[] source, int sourceLength);

        [DllImport("zlib32")]
        private static extern ZLibError compress2(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality);

        [DllImport("zlib32")]
        private static extern ZLibError uncompress(byte[] dest, ref int destLen, byte[] source, int sourceLen);

        public Compressor32()
        {
        }

        public string Version
        {
            get
            {
                return zlibVersion();
            }
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return compress(dest, ref destLength, source, sourceLength);
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            return compress2(dest, ref destLength, source, sourceLength, quality);
        }

        public ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return uncompress(dest, ref destLength, source, sourceLength);
        }
    }

    public sealed class Compressor64 : ICompressor
    {
        [DllImport("zlib64")]
        private static extern string zlibVersion();

        [DllImport("zlib64")]
        private static extern ZLibError compress(byte[] dest, ref int destLength, byte[] source, int sourceLength);

        [DllImport("zlib64")]
        private static extern ZLibError compress2(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality);

        [DllImport("zlib64")]
        private static extern ZLibError uncompress(byte[] dest, ref int destLen, byte[] source, int sourceLen);

        public Compressor64()
        {
        }

        public string Version
        {
            get
            {
                return zlibVersion();
            }
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return compress(dest, ref destLength, source, sourceLength);
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            return compress2(dest, ref destLength, source, sourceLength, quality);
        }

        public ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return uncompress(dest, ref destLength, source, sourceLength);
        }
    }

    public sealed class CompressorUnix32 : ICompressor
    {
        [DllImport("libz")]
        private static extern string zlibVersion();

        [DllImport("libz")]
        private static extern ZLibError compress(byte[] dest, ref int destLength, byte[] source, int sourceLength);

        [DllImport("libz")]
        private static extern ZLibError compress2(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality);

        [DllImport("libz")]
        private static extern ZLibError uncompress(byte[] dest, ref int destLen, byte[] source, int sourceLen);

        public CompressorUnix32()
        {
        }

        public string Version
        {
            get
            {
                return zlibVersion();
            }
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return compress(dest, ref destLength, source, sourceLength);
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            return compress2(dest, ref destLength, source, sourceLength, quality);
        }

        public ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return uncompress(dest, ref destLength, source, sourceLength);
        }
    }

    public sealed class CompressorUnix64 : ICompressor
    {
        [DllImport("libz")]
        private static extern string zlibVersion();

        [DllImport("libz")]
        private static extern ZLibError compress(byte[] dest, ref ulong destLength, byte[] source, int sourceLength);

        [DllImport("libz")]
        private static extern ZLibError compress2(byte[] dest, ref ulong destLength, byte[] source, int sourceLength, ZLibQuality quality);

        [DllImport("libz")]
        private static extern ZLibError uncompress(byte[] dest, ref ulong destLen, byte[] source, int sourceLen);

        public CompressorUnix64()
        {
        }

        public string Version
        {
            get
            {
                return zlibVersion();
            }
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            ulong destLengthLong = (ulong)destLength;
            ZLibError z = compress(dest, ref destLengthLong, source, sourceLength);
            destLength = (int)destLengthLong;
            return z;
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            ulong destLengthLong = (ulong)destLength;
            ZLibError z = compress2(dest, ref destLengthLong, source, sourceLength, quality);
            destLength = (int)destLengthLong;
            return z;
        }

        public ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            ulong destLengthLong = (ulong)destLength;
            ZLibError z = uncompress(dest, ref destLengthLong, source, sourceLength);
            destLength = (int)destLengthLong;
            return z;
        }
    }

    public enum ZLibError : int
    {
        VersionError = -6,
        BufferError = -5,
        MemoryError = -4,
        DataError = -3,
        StreamError = -2,
        FileError = -1,

        Okay = 0,

        StreamEnd = 1,
        NeedDictionary = 2
    }

    public enum ZLibQuality : int
    {
        Default = -1,

        None = 0,

        Speed = 1,
        Size = 9
    }
}